This invention generally relates to a device for controlling the tone arm of a record player, and more particularly, the present invention relates to a device for controlling vertical and/or horizontal attitudes of the tone arm equipped with a moving coil type pickup.
In a record player having a pickup of moving coil type, the vertical and horizontal positions of the moving coil with respect to the provided magnetic field of the pickup has to be controlled so that the moving coil, which generates an output voltage indicative of the picked up information, is kept at an optimum position with respect to the magnetic field irrespective of the warp or curve of the playing phonograph disk. Namely, if the moving coil operates off the optimum position, the output signal from the pickup would be distorted.
In some conventional record players, the output signal of the moving coil type pickup is processed to produce a tone arm control signal. The vertical and horizontal position of the moving coil with respect to the yoke is thus controlled so that the moving coil(s) is(are) always kept at a right position irrespective of the warp and/or eccentricity of the disk. However, since the moving coil per se produces its output signal which is in proportion to the moving velocity thereof, the low frequency output voltage indicative of the warp of the disk available for controlling the arm is very low. For this reason, in the conventional record players, the position of the moving coil could not be accurately controlled to the optimum position especially in the case that the up-down frequency of the moving coil is very low.